Every time I have a look at WP ecommerce solutions, the most notable factor is the number of rants about how WP ecommerce sucks, the people selling it are evil, and it simply doesn't work. However, I also hear that it depends on what you want to do with it. If all you are doing is something simple, like me, like selling graphics files, no shipping etc, it works quite well. It doesn't work well with multiple options for a SKU or multiple options for shipping - you should get the shopp plugin. Can anyone here confirm that? If all I am doing selling is 25 different graphics files, would WP ecommerce be a step up form paypal buttons? In case your asking why, I hate paypal and would like to be able to accept other payments. (I have a regular tangible goods ecommerce site that is hooked into authorize.net gateway)
WP Ecommerce works alright but I would go with Woo Commerce instead as it's a bit easier to setup the way you want, it's easier to customize plus it has all sorts of add-ons you can buy. I use this for all of my e-commerce projects now and both my customers and I have been satisfied.
Magento is the platform for ecommerce solutions... i have used it for my store and i am very satisfied with it..